If you are replacing an internal door, the first question is nearly always the same: what size do I need? The good news is that standard internal door sizes in the UK are far more consistent than window sizes, so there is a real chance your opening matches a common size. Here is the list you need, in both metric and imperial, plus what to do when your opening is one of the awkward ones.
We fit doors across York and North Yorkshire, so this covers the sizes you will actually meet in local homes.
Most modern internal doors sold in the UK come in metric sizes. Heights and widths are given in millimetres, and the standard thickness is usually 35mm for lighter doors or 40mm for heavier ones.
Common metric widths (all at a standard 1,981mm height):
The standard metric height is 1,981mm, with 2,040mm available for taller openings.
Plenty of older homes were built to imperial sizes, and doors are still sold to match. The standard imperial height is 6ft 6in, with widths including:
You will notice the imperial and metric sizes line up closely, because the metric sizes were designed to replace the old imperial ones. In practice, a 2ft 6in door and a 762mm door are effectively the same thing.
If you had to bet, a 762mm wide by 1,981mm high door (2ft 6in by 6ft 6in) is the safest guess for a general internal door in a modern UK home. Bedroom and bathroom doors are often 686mm. That said, always measure rather than assume, because houses vary and previous owners change things.
Before you order, measure the door itself if you are matching an existing one, or the structural opening if you are working from scratch.
If your measurements sit between standard sizes, you are dealing with a non-standard opening, which is very common in period properties around here.
Not every opening plays nicely with a catalogue size, especially in older cottages and terraces. You have a few options:
If in doubt, it is worth having someone measure and advise, because a door that binds or leaves a big gap is a daily annoyance.
If the door is a fire door, for example in some flats, lofts or between a house and an integral garage, there are separate requirements covering size, construction and gaps. These rules change and depend on the property, so check the current Building Regulations and confirm with your local authority where fire safety is involved. Do not trim a fire door beyond the maker's stated allowance, as it can affect its rating.
Internal door prices vary with material, style and glazing. As a rough 2026 guide, a standard internal door often costs somewhere between about 40 and 200 pounds for the door itself, with oak, glazed and fire-rated doors higher, plus fitting on top. Made-to-measure doors cost more. These are ballpark figures, so ask for a quote for your project. If you are updating your entrance at the same time, our composite front doors and uPVC doors are worth a look.
The most common is 762mm wide by 1,981mm high (2ft 6in by 6ft 6in) at 35mm thick. Bedroom and bathroom doors are often 686mm wide. Always measure your own opening to be sure.
Usually a little, yes. Most doors have a lipping that allows a small amount to be planed off each edge, but there is a limit set by the maker. Fire doors have strict limits, so check before cutting.
Either trim a larger standard door within the maker's allowance, or order a made-to-measure door for anything unusual, heavy or glazed. Odd openings are common in older homes.
Both are sold. Modern doors are usually metric, while many older homes use imperial sizes. The two line up closely, so a 2ft 6in and a 762mm door are effectively the same.
Planning a run of new doors? Download our latest brochure to see styles and finishes, or request a free quote and we will help you get the sizes right.